1. Field of the Invention
The present invention relates to a method for estimating DC (Direct Current) motor coil temperature without using a temperature sensor, a DC motor control method based upon an estimated coil temperature, and their devices.
2. Description of Related Art
From the past, an air conditioner device comprises a compressor driven by a motor. Therefore, a disadvantage is necessarily prevented from occurrence such that oil is diluted so as to cause burning in. For this reason, it is required that a temperature in an interior of a compressor is detected as an indicator to which extent preheating driving is to be carried out.
When a temperature in an interior of a compressor is measured by inserting a thermocouple or the like in the interior of the compressor for realizing the demand, great increase in cost is caused. Therefore, it is proposed and practiced that a temperature of an outlet pipe of a compressor is detected and a temperature in an interior of the compressor is estimated from the detected temperature.
When a method is employed for estimating a temperature in an interior of a compressor from a temperature of an outlet tube of the compressor, a disadvantage arises in that a temperature estimation error becomes greater for a case where the compressor is stopped and is applied preheating driving or the like.
To dissolve the disadvantage, a thermistor may be provided for directly measuring a temperature of a body of a compressor. In this case, increase in cost is caused.
Similar disadvantages arise for other devices each driven by a motor.